Standard 34 describes a shorthand way of naming refrigerants and assigns safety classifications based on toxicity and flammability data, while Standard 15 establishes procedures for design, construction, installation, inspection, testing, and operation of the equipment and systems using those refrigerants. ASHRAE offers the standards as a set. Here are highlights of what's new in the 2013 editions:

ASHRAE Standard 15-2013:

Standard 34-2013:

• Clarifies and modifies definitions
• Adds 1 new single-compound refrigerant and 14 new refrigerant blends
• clarifies section 7.3, Requirements for Data Calculations, and 9.6, Toxicity Information, for consistency
• Changes the flammability safety classification of refrigerants 32, 143a, 717 and 1234yf from Class 2 to Class 2L based on the optional burning velocity measurement
• Modifies the definition of Workplace Environmental Exposure Level (WEEL) and adds a reference for AIHA WEEL
• Clarifies the conditions for bubble point in Sections B2.4.1 and B2.4.2 of Normative Appendix B.2, Fractionation Analysis
• Better defines experimental verification of models used to identify WCFF fractionated compositions, and allows vaporliquid equilibrium (VLE) data only to be used for experimental verification